Five novel tin Schiff base complexes with histidine analogues (derived from the condensation reaction between L-histidine and 3,5-di-tert-butyl-2-hydroxybenzaldehyde) have been synthesized and characterized. Characterization has been completed by IR and high-resolution mass spectroscopy, 1D and 2D solution NMR (1H, 13C？？and 119Sn), as well as solid state 119Sn NMR. The spectroscopic evidence shows two types of structures: a trigonal bipyramidal stereochemistry with the tin atom coordinated to five donating atoms (two oxygen atoms, one nitrogen atom, and two carbon atoms belonging to the alkyl moieties), where one molecule of ligand is coordinated in a three dentate fashion. The second structure is spectroscopically described as a tetrahedral tin complex with four donating atoms (one oxygen atom coordinated to the metal and three carbon atoms belonging to the alkyl or aryl substituents), with one molecule of ligand attached. The antimicrobial activity of the tin compounds has been tested against the growth of bacteria in vitro to assess their bactericidal properties. While pentacoordinated compounds 1, 2, and 3 are described as moderate effective to noneffective drugs against both Gram-positive and Gram-negative bacteria, tetracoordinated tin(IV) compounds 4 and 5 are considered as moderate effective and most effective compounds, respectively, against the methicillin-resistant Staphylococcus aureus strains (Gram-positive). 1. Introduction The use of metal complexes as chemotherapeutic agents in the treatment of illness, which are a major public health concern, appears as a very attractive alternative. The success of cisplatin for the treatment of testicular and ovarian cancer attracted research attention to other metal-based antineoplastic agents. Metal-based compounds are of particular interest due to their physical and chemical properties. Properties such as ligand exchange rates, redox properties, oxidation states, coordination affinities, solubility, biodisponibility, and biodistribution could be modified in order to increase the therapeutic effect while reducing the side effects. Although the design of a metal-based compound with good therapeutic index is still rather empirical, a number of potential metal-based bactericide compounds have been fully described in the literature. The evidence about specific or selective bonding of metals and organometallic species to donor sites in biological structures is very limited, so trustable mechanisms of biological activity and valid structure-activity relationships are limited as well. One approach that
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